Said wiper ring for downhole tool

ABSTRACT

A drilling jar having a tubular mandrel reciprocally disposed in a tubular housing and extending upwardly from the upper end of the housing. The upper end of the housing includes O-ring fluid seals located between the housing and the mandrel. The upper end of the housing forms an upwardly facing lower impact surface which abuts a downwardly facing upper impact surface around the mandrel. A wiping ring is anchored within the housing and extends upwardly within and beyond the lower impact surface into peripheral wiping contact with the mandrel at a point above the impact surface. A downwardly facing groove is formed within the upper impact surface to receive the upper end of the wiper ring when the two impact surfaces are in contact. The upper end of the housing slopes downwardly and outwardly from just below the upper end of the wiping ring to the interior edge of the lower impact surface.

United States Patent [72] lnventor James L. Newman 1321 Glen Cove, Richardson, Tex. 75080 211 Appl. No. 710,089 [22] Filed Mar. 4, 1968 [45] Patented June 15, 1971 Continuation-impart 01 application Ser. No.

488,333, Sept. 20, 1965, now Patent No. 3371730, dated Mar. 5, 1968.

[54] SAND WIPER RING FOR DOWNHOLETOOL 15 Claims, 10 Drawing Figs.

[52] US. Cl 175/300, 277/212 [51] 1nt.Cl F2lb 1/10 [50] Field of Search..... 1751293- [56] References Cited UNITED STATES PATENTS 2,595,592 5/1952 Magnuson 277/212 X 2,670,930 3/1954 Farrar 175/293 X 2,701,155 2/1955 Estel 277/152 2,762,638 9/1956 Brown 277/15 2,867,462 l/l959 Nielsen 277/152 3,221,826 12/1965 Webb 175/297 3,396,807 9/1968 Menton 175/293 3,371,730 3/1968 Newman 175/300 Primary Examiner-James A. Leppink Assistant Examiner-Richard E. Favreau AttorneyRichards, Harris & Hubbard ABSTRACT: A drilling jar having a tubular mandrel reciprocally disposed in a tubular housing and extending upwardly from the upper end of the housing. The upper end of the housing includes O-ring fluid seals located between the housing and the mandrel. The upper end of the housing forms an upwardly facing lower impact surface which abuts a downwardly facing upper impact surface around the mandrel. A wiping ring is anchored within the housing and extends upwardly within and beyond the lower impact surface into peripheral wiping contact with the mandrel at a point above the impact surface. A downwardly facing groove is formed within the upper impact surface to receive the upper end of the wiper ring when the two impact surfaces are in contact. The upper end of the housing slopes downwardly and outwardly from just below the upper end of the wiping ring to the interior edge of the lower impact surface.

SAND WIPER BJNG FOR DOWNHOLE TOOL RELATED APPLICATIONS Sept. 20, I965, which issued as US. Pat. No. 3,371,730 on Mar. 5, 1968.

BACKGROUND OF THE INVENTION This invention relates generally to downhole tools, and more particularly, but not by way of limitation, relates to a drilling jar having a wiper ring for protecting a resilient sealing ring housed in an upward locking gland through which arod reciprocates in an environment of fluid entrained sand.

In conventional rotary drilling, the bit is driven by a drill stem comprised of a number of threaded interconnected joints of drill pipe and drill collars. A special mud is usually pumped downwardly through the drill string and through the bit and recirculated upwardly through the annulus to carry the cuttings from the borehole and to contain subsurface pressures. The bit is customarily loaded with a portion of the weight of the drill stem to increase the rate of penetration. The drill collars, which are of uniform maximum diameter, usually provide this weight and also stiffen the stem immediately above the bit to produce a straighter hole. As a result of the smooth and uniform surface, the drill collars sometimes stick to the wall of the borehole. The drill pipe on the other hand has a substantially reduced outside diameter, except for the interconnecting tool joints which are of the same diameter as the drill collars, and is not subject to sticking. When a portion of the weight of the drill pipe is applied to the drill collars, however, the pipe tends to bend. This may also cause the hole to be crooked.

Drilling jars have been used to some extent to deliver either an upwardly or downwardly directed impact force on the drill string in order to free stuck drill collars. These drilling jars and bumper subs can also be used during normal drilling opera tions to isolate the weight of the drill pipe from the drill collars and prevent a crooked hole due to bending of the drill pipe. However, before a drilling jar or bumper sub can be used during normal drilling operations, it is very important that the high-pressure drilling fluid being pumped downwardly through the drill string be sealed from the lower-pressure fluid in the annulus by an effective sea] at the sliding joint between the housing and mandrel. If this seal should begin to leak, the highly abrasive drilling fluid will quickly erode the housing, which may then be so weakened as to separate.

Conventional resilient O-ring seals are customarily used for this purpose. However, if the O-rings are disposed in an upwardly locking gland, as it is desirable to do for other reasons, an annular sand trap is formed between the upper end of the gland housing and the reciprocating rod which traps'the very fine abrasive particles carried in the drilling mud. Then as the rod reciprocates, the abrasive particles rather quickly destroy the sealing capability of the O-rings. Both resilient wiper rings and metal scraper rings have been used to scrape sand from the rod and protect the O-rings, but these rings are also positioned within the gland housing so as to form an upwardly locking sand trap. During use the trapped sand first renders the wiper or scraper ring ineffective, then attacks the O-ring seals.

SUMMARY OF THE INVENTION In accordance with this invention, a wiper ring is provided which does not collect sand in such a manner as to render the wiper ring ineffective. This is achieved by extending the lip of the wiper ring above the upper end of the gland housing by a distance such that sand cannot collect around the lip. In more specific aspects of the invention, the upper end of the housing also slopes downwardly and outwardly away from a point adjacent the upper end of the lip to protect the resilient lip from impact. In a further specific embodiment, the wiper ring is used in a drilling jar and the upper end of the housing has an annular, upwardly facing impact surface disposed below the upper end of the lip of the wiper ring, and the mandrel which reciprocates through the gland has a mating downwardly facing impact surface disposed around a downwardly facing groove for receiving the lip of the wiper ring. In accordance with another aspect of the invention, the-upwardly facing impact surface is the upper end of a cylindrical knocker ring and a resilient wiper ring is retained within the knocker ring and protected by a metal protector ring which is secured within the knocker ring.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of this invention are set forth in the appended claims. The invention itself, however, as well as other objects and advantages thereof, may best be understood by reference to the following detailed description of illustrative embodiments, when read in conjunction with the accompanying drawings, wherein:

FIGS. la, lb and 1c, collectively, are a longitudinal sectional view of a drilling jar constructed in accordance with this invention with the mandrel in the closed position;

FIG. 2 is a sectional view taken substantially on lines 2-2 of FIG. 1b;

FIG. 3 is a sectional view taken substantially on lines 3-3 of FIG. lb;

FIG. 4 is a simplified view, partially in section, of the drilling jar of FIGS. la- 1c with the mandrel in the extended position;

FIG. 5 is a sectional view taken on the same lines as FIG. 2 but showing the jar in the unlatched position;

FIG. 6 is a sectional view taken on the same lines as FIG. 3 but showing the jar in the unlatched position;

FIG. 7 is a partial longitudinal sectional view showing an alternative embodiment of the invention; and

FIG. 8 is a partial longitudinal sectional view showing another embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, a drilling jar constructed in accordance with this invention is shown in FIGS. 1a, lb and 1c. The drilling jar is comprised of a tubular housing indicated generally by the reference numeral 10 and a tubular mandrel assembly, indicated generally by the reference numeral 12, which is extensibly received within the housing 10. The mandrel assembly 12 includes a tool joint portion 14, which is in the form of a drill collar sub a few feet in length having a conventional box tool joint at the end. A knocker collar 16 is threaded onto a portion of the mandrel body 18 and abuts against an annular shoulder 20. A pair of O-ring seals 22 and 24 is provided on opposite sides of the threads 26 to prevent sanding of the threaded connection. The collar 16 has a skirt portion 28 which extends downwardly over a tubular portion 30 to form an annular, downwardly facing open cavity 32 to lessen the effects of sanding as will hereafter be described. The skirt portion 28 also lessens the stress on the mandrel adjacent the threads 26 by spacing the member 54 from the threads 26.

A mandrel sleeve 34 is disposed around the mandrel body 30 and secured against rotation by an elongated key 36, shown in dotted outline in FIG. lb, and which is received in grooves in the body 30 and sleeve 34 as shown in FIGS. 2 and 3. The groove in the mandrel sleeve 34 extends to the end so that the sleeve may be slipped over the body after the key has been inserted in the slot in the body to facilitate assembly. The mandrel sleeve 34 is secured against longitudinal movement on the mandrel body 30 by means of an annular shoulder 37 on the interior surface of the mandrel sleeve which abuts an annular shoulder 38 on the mandrel body 30, and the end 40 of a tubular wash pipe 42 which is connected to the end of the mandrel body 30 by threads 44. O-ring paris 46 and 48 disposed on either side of the threads 44 provide a fluid tight connection between the wash pipe 42 and the mandrel body 30. An annular shoulder 50 within the wash pipe 42 abuts against the end of the mandrel body 30. Thus the sub 14, knocker collar 16, mandrel body 30, mandrel sleeve 34 and wash pipe 42 are rigidly interconnected, and a fluid passageway 52 extends longitudinally through the mandrel assembly 12.

The housing is comprised of a sealing ring collar 54 having an annular knocker skirt 56 at one end which mates with and bumps the skirt 28 and forms an annular, open cavity 58, and a lower end 59 which engages the mandrel sleeve hereafter described when the mandrel is fully extended. A number of bores 60 extend radially through the knocker collar 16 to vent sand from cavity 32. The collar 54 is slidably disposed around the constant diameter portion of tubular mandrel body 30 and a pair of one-piece O-ring seals 62 provides a peripheral fluid seal between the sealing collar 54 and the tubular body 30. A pair of metallic nonextrusion rings 64 is provided on each side of each of the O-rubg seals 62. The tubular body 70 of the housing 10 is connected to the collar 54 by threads 72. A pair of O-rings 74 provides a peripheral fluid seal between the collar 54 and tubular body 70. A wash pipe cylinder liner 76 is inserted in the other end of the body 70. The end of the liner 76 engages an inturned annular shoulder 78 within the body 70 which acts as a stop. A second sub 80 is connected to the liner 76 by threads 82 and the end of the sub 80 engages an annular shoulder 86 on the liner 76, The sub 80 is connected to the housing body 70 by threads 84 and thus secures the liner 76 in place in the body 70. A pair of O-ring seals 88 provides a peripheral fluid seal between the sub 80 and liner 76 to prevent fluid pressure in the passageway 52 from passing through the threaded connections 82 and 84. A pair of O-rings 90 provides a peripheral seal between the body 70 and the wash pipe liner 76 to prevent the escape of fluid from the annulus formed between the mandrel 12 and the housing 10 through the threaded connection 84. The sub 80 may be several feet in length and provided with standard tool joint, such as the pin 92.

A mechanical lug means, indicated generally by the reference numeral 100 in H6. 4, is formed on the mandrel sleeve 34 and is comprised of a pair of upstanding, longitudinally extending lugs 102 and 104 (see F105. 2, 3 and 6). Circumferentially extending lugs 106, 107, 108 and 109 extend counterclockwise, when viewed from the large end of the mandrel, from the longitudinal lug 102, and lugs 110, 111, 112 and 113 extend circumferentially and counterclockwise from the longitudinal lug 104. The mechanical lug means 100 cooperatively engages a similar lug means formed in the interior surface of the housing body 70 by a pair of longitudinally extending grooves 120 and 122. The longitudinally extending groove 120 is sufficiently wide to permit longitudinal movement of both the longitudinally extending lug 102 and the circumferentially extending lugs 106-109. Similarly, the longitudinally extending groove 122 is so sized and spaced as to pass the longitudinally extending lug 104 and the circumferentially extending lugs 110-113 in the longitudinal direction. Circumferential grooves 124, 125, 126, 127, 128 and 129 intersect the longitudinally extending grooves 120 and 122 and are spaced to form inwardly directed lugs 130, 131, 132, 133 and 134 and to also simultaneously receive the circumferentially extending lugs of the means 100. For example, when the mandrel is in the retracted position illustrated in FIGS. la-lc, the lugs 106 and 110 are received by the groove 126, lugs 107 and 111 by the groove 127, lugs 108 and 112 by the groove 128, and lugs 109 and 113 by groove 129. When the mandrel is in the extended position illustrated in FIG. 4, lugs 106 and 110 are received in groove 124, lugs 107 and 111 in groove 125, lugs 108 and 112 in groove 126 and lugs 109 and 113 in groove 127. When the mandrel is rotated in the counterclockwise direction, the circumferentially extending lugs 106-113 enter the appropriate circular grooves and the inwardly directed lugs 130-134 in the housing 10 prevent longitudinal movement of the mandrel relative to the housing. When the mandrel is rotated clockwise, the longitudinal lugs 102 and 104 on the mandrel engage the lugs -134 on the housing to transmit torque between the mandrel and housing while permitting true longitudinal movement between the mandrel and housing.

The diameter of the tubular body 30 of the mandrel 12 is of constant diameter down to the shoulder 38, and the wash pipe 42 is of the same diameter as the body 30 from the annular shoulder to its end. O-ring seals 142 are disposed around the wash pipe 42 adjacent the end thereof. Metal rings 144 are disposed on each side of the O-rings 142 to protect the O-rings against extrusion and from being abraded by entry into the scarf between the wash pipe 42 and the wash pipe liner 76. Because the diameters of the tubular body 30 and wash pipe 42 of the mandrel are equal, the volume of the annular cavity formed between the mandrel and housing by the sliding O-ring seals 62 and 142 and the stationary O-ring seals 74, 90, 46 and 48 remains constant as the mandrel moves longitudinally within the housing 10. The annular cavity thus formed may be completely filled by a suitable fluid, preferably a relatively light lubricating oil, through the filler plugs 146 and 148.

A top resilient wiper ring 150 is disposed within the annular cavity 58 and has an enlarged base portion which is retained in place by a snap ring 152. The wiper ring 150 has a long annular lip 1500 which extends substantially above the abutting annular surfaces of the knocker ring 56 so that any sand accumulating on the surface of the tubular portion 30 will be wiped off and tend to pass outwardly over the shoulder or through the vent bores 60 and so that the upper end of the sealing lip engages the mandrel at a point above the sand that will usually fill cavity 58. The downwardly facing cavity 32 provides a recess for receiving the lip 1500. The ports 60 provide an avenue of escape for fluid trapped in the cavity 32 as the tool closes and reduces the chances of cakes of sand forming which would destroy lip 1500.

A standard grease fitting 154 is in fluid communication with an annular groove 155 formed in the interior surface of the collar 54 between the sealing rings 62 and the wiper ring 150. Grease pumped through the fitting 154 will pass under the lip 150a to clean out the sand and other crud which may have collected under the lip and will also provide lubrication.

A similar wiper ring 156 is positioned around the lower end of the wash pipe 42 and has an annular lip 156a which wipes the interior surface of the wash pipe liner 76 clean. The wiper ring 156 is secured in place by a spacer ring 158 and a snapring 160.

ln order to assembly the drilling jar, the knocker ring 16 is first threaded onto the mandrel. Next the sealing collar 54, with the wiper ring 150 and O-ring seals 62 in place, is passed over the end of the tubular body 30. The key 36 can then be positioned in the slot in the surface of the tubular body 30 and the mandrel sleeve 34 slipped over the body 30 and over the key. The wash pipe 42 is then threaded on the end of the body 30 and tightened until the mandrel sleeve 34 is locked securely in place. The lower sub 80 may then be threaded over the wash pipe liner 76 at the threads 82 and this assembly inserted in the end of the housing body 70 and connected by threads 84. This much of the housing may then be passed over the mandrel assembly 12, including the wash pipe 42 and the mandrel sleeve 34, and threaded onto the collar 54 by the threaded connection 72. The annular cavity formed between the mandrel l2 and housing 10 by the annular O-ring seals 62, 74, 90, 142, 46 and 48 may then be filled with a lubricating oil through the plugs 146 and 148. The upper wiper 150 may be lubricated by injecting a grease through the fitting 154. The drilling jar is then ready for use.

In operation, the tool joint 14 at the end of the mandrel 12 is preferably a box and is connected to the section of the drill pipe extending to the surface. The pin 92 on the end of the sub 80 will customarily be threaded into the upper end of the drill collars which extend downwardly to the drill bit and are of the same diameter as the housing 10. During normal drilling operations, the drill string is rotated in the clockwise direction when looking downhole and the longitudinally extending lug 102 engages the lugs 130--134 and transmits the necessary torque through the drilling jar to the drill bit. However, since the circumferentially extending lugs l06-1 13 are disposed in the longitudinally extending grooves 120 and 122 of the housing 10, a force will be transmitted longitudinally through the drilling jar only at the upper or lower limits of the stroke of the mandrel within the housing. Thus, if the mandrel is properly positioned, the weight of the drill pipe above the drilling jar will be totally suspended from the derrick and only the weight of the drill collars will be supplied to the drill bit. As a result, the weight applied to the bit is uniformly controlled as the bit makes hole. This permits an increase in the bit loading for maximum penetration rate without increasing the danger of inadvertently overloading the bearings of the bit.

In the event the string of drill collars should become struck in the borehole, the drilling jar is immediately available to assist in removing the drill collars from the hole. In order to strike an upwardly directed impact force on the drill collars, the drill string is lowered until the skirt 28 of the collar 16 engages the skirt 56 of the collar 54. Then the drill string is rotated counterclockwise until the circumferentially extending lugs 106ll3 have entered the lower grooves 126129 as illustrated in FIGS. 1a-1c. The drill string is then lifted upwardly to stretch the string to a preselected tension. The string of drill pipe will stretch more than the total stroke of the mandrel 12 in the housing 10 when the proper amount of force is applied. Then the drill pipe is rotated in the clockwise direction until the circumferentially extending lugs 106113 on the mandrel clear the lugs 130-134 in the housing. The mandrel 12 then moves upwardly with essentially unrestrained force until the upper end of the mandrel sleeve 34 impacts the lower end 59 of the collar 54 thereby delivering an upwardly directed blow to the housing 10 and therefore to the string of drill collars.

On the other hand, if a downwardly directed impact blow is to be applied to the drill collars, the mandrel 12 is raised to the position illustrated in FIG. 4, the drill string rotated in the counterclockwise direction to engage the lugs 106-113 in the upper four circumferentially extending grooves 124-127, the drill stem lowered to apply the desired weight to the mandrel 12 and the drill string then rotated in the clockwise direction. When the lug 106 clears the lugs 130-133, the mandrel travels downwardly at a very rapid rate until the skirt 28 of the knocker collar 16 contacts the skirt 56 of the collar 54 to deliver an impact force to the housing 10 and therefore to the string of drill collars.

Due to the fact that all working parts of the drilling jar are contained in a clean lubricating fluid, the drilling jar has a long life and is not susceptible to excessive wear due to movement in an abrasive, sand filled drilling mud as in the conventional mechanical jar. Further, the drilling jar may be safely used during normal drilling operations because the danger of leakage from the interior of the drilling jar to the annulus is substantially eliminated because the fluid would always have to pass through a minimum of two separate seals. For example, before the fluid could pass from the interior of the mandrel through the joint between the body 30 and wash pipe 42 to the annulus, it would have to pass through O-ring seals 48 and 46 and then through either O-ring seals 90, 62 or 74. Since O-ring seals 46 and 48 are static, the danger of leakage is virtually nonexistent. In order for drilling fluid to pass through the sliding seals 142 to the borehole annulus, the mud would have to displace the lubricating fluid and pass through the sliding sealing rings 62, or through the static sealing rings 74 and 90, in addition to the standard threaded couplings 72 or 84, respectively, which are customarily fluid tight without O-rings. In addition to controlling the weight on the drill bit, the drilling jar is always available to free stuck drill collars by immediately delivering either an upwardly or downwardly directed impact force of preselected magnitude to the drill collars.

By completely filling the annulus with lubricating liquid at surface temperature and pressure, the increase in volume of the lubricating liquid due to the normal increase in temperature with depth in the borehole will tend to offset the increase in pressure with depth, thus resulting in a lower differential pressure across the seals. For example, at a drilling depth of 10,000 feet, the bottom hole pressure may be on the order of 8,000 p.s.i. and the temperature on the order of 200 F. As a result of the temperature, the internal pressure of the lubricating liquid may be on the order of 5,000 p.s.i. so that only a 3,000 p.s.i. differential is placed across the seals, as compared to an 8,000 p.s.i. differential, thus tending to increase the useful life of the seals and reducing the likelihood of a failure.

Another embodiment of the invention is illustrated in FIG. 7. The embodiment shown in FIG. 7 is substantially identical to that described in FIGS. 1-6 and corresponding components are therefore designated with the same reference characters. It will be noted that this embodiment includes a wiper ring which is disposed in an upwardly facing, annular, open-topped chamber formed between the interior surface of the cylindrical knocker ring 56 and the exterior surface of the tubular rod portion of the mandrel body 18. A retaining ring 152, which is snapped into an annular groove in the interior face of the knocker ring 56, secures the enlarged body portion of the wiper ring 150 in the annular chamber. The wiper ring has an elongated lip which is in sliding, peripheral engagement with the exterior surface of the rod portion of the mandrel 18 at a point substantially above the upwardly facing impact face 56a at the upper end of the knocker ring 56.

The interior surface of the wiper ring 150 has a taper of about 1 over the length 1511b to provide a stretch fit and this entire surface may be in sliding contact with the mandrel. The interior diameter of the wiper ring 150 at the root or body portion may be greater than the diameter of the mandrel so as to provide an annular cavity-1150c which may be be filled with grease and which will also permit the body of the ring to be forced downwardly within the knocker ring 56 to provide a tight fit and thereby securely hold the wiper ring in place.

A protector ring 200 is secured within the knocker ring 56 above the retainer ring 152 by means of a press fit. The protector ring 200 protects the lower portion of the lip 150a and also prevents the accumulation of sand in the annular trough otherwise formed above the root of the wiper ring 150. The outer surface 200a of the protector ring 200 slopes downwardly and outwardly from a point just below the tip of the sealing lip 150a to the level of the upwardly facing, annular impact surface 50a. The interior surface of the protector ring 200 is conformed so that the upper tip of the protector ring engages the lip 150a, while the lower interior surface is spaced from the wiper ring 150. This arrangement securely holds the tip of the wiper ring against the mandrel 52, while permitting the lower end of the wiper ring to flex to some extent.

The wiper ring 150 is typically fabricated by machining a block of Teflon, or by molding from a relatively hard, but flexible synthetic rubber material. If desired, however, the wiper ring 150 can be fabricated from substantially any material which is sufficiently softer than the mandrel 18 so as to not scar the mandrel. The protector ring 200 is typically fabricated from brass, but may also be fabricated from substantially any material having the necessary degree of rigidity and toughness to protect the wiper ring 150.

A lubricating port 216 and a cleanout port 218 are provided on opposite sides of the housing body and are in fluid communication with the annular groove 155. Plugs 220 and 222 are threaded into the ports during normal operation to retain grease or other substantially noncompressible lubricating fluid in the annular space between the housing and mandrel, and between the O-ring seal 62 and the wiper ring 150. For servicing, the plugs can be removed and grease pumped form one port to the other to flush the annular groove 155. Then one of the plugs can be replaced and grease pumped by the wiper ring 150 to clean and fill the remainder of the annular space and the second plug replaced. The noncompressible fluid is then trapped by the O-ring seals and assists in excluding foreign fluids and abrasive particles from the annular space when the tool is subject to downhole pressures and the mandrel reciprocated in the housing.

Another embodiment of the invention is illustrated in FIG. 8. The embodiment illustrated in FIG. 8 is for a tool of substantially larger diameter. As a result, the wiper ring 210 and the protector ring 212 have different cross-sectional configurations, but still employ the same basic functional parts. The lip 210a of the wiper ring extends above the upper end of the protector ring 212 which slopes downwardly to the impact surface 560 on the knocker ring 56. However, the retainer ring 152 is eliminated and the protector ring 212 is used to retain the wiper ring 210 in place within the knocker ring 56. The protector ring 212 may again be press fitted within the knocker ring 56, as illustrated, or may be threaded into the knocker ring or otherwise secured in place.

The protector ring 212 in effect becomes a part of the sealing gland housing for the sealing rings 62, and provides an upper end which slopes downwardly and outwardly from the upper end of the sealing lip 210a so as to virtually eliminate the possibility that sand will cake above the lip and adversely affect its operation. The combination of this structure with the knocker sleeve 16 on the mandrel body still permits the use of the upper end of the knocker ring 56 to deliver an impact blow in the operation of the drilling jar or bumper sub. While the wiper ring assembly herein described has been conceived and designed in the specific environment of a drilling jar or bumper sub having an annular impact surface at the upper end of the housing, the wiper ring has broad use in connection with any tool which operates in a fluid environment containing entrained abrasive particles wherein a rod must reciprocate with a vertical component of motion within an upwardly facing packing gland for providing a fluid seal around the rod.

Although preferred embodiments of the invention have been described in detail, it is to be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope ofthe invention as defined by the appended claims.

What 1 claim is:

1. In a drilling tool for delivering a longitudinally directed impact, the combination of:

a tubular housing,

a tubular mandrel reciprocally disposed in the housing and extending above the housing,

a resilient fluid sealing ring disposed within the housing and around the mandrel to provide a peripheral fluid seal between the upper end of the housing and the mandrel,

an upwardly facing impact surface formed at the upper end of the housing having an internal diameter greater than the external diameter of the mandrel,

a downwardly facing impact surface formed around the mandrel above the housing for engaging the upwardly facing impact surface and having an internal diameter at the lower end greater than the external diameter of the portion of the mandrel reciprocally disposed in the housing to form a downwardly facing annular groove, and

a wiper ring secured within the housing, the wiper ring having a lip which extends upwardly and engage the periphery of the mandrel at a point above the upwardly facing impact surface and the downwardly facing impact surface when the two surfaces are in contact.

2. The combination defined in claim 1 further characterized port means formed in the mandrel above the downwardly facing impact surface extending between the downwardly facing annular groove and the exterior of the mandrel to vent fluid from the downwardly facing annular groove as the jar closes.

3. The combination defined in claim 1 wherein:

the upper end of the housing tapers downwardly and outwardly from the lip of the wiper ring to the upwardly fac ing impact surface.

4. The combination defined in claim 1 further characterized a protector ring secured to the housing within the upwardly facing impact surface for protecting a portion of the lip of the wiper ring, the upper surface extending from the wiper ring at a point below the upper end of the lip downwardly and outwardly to the upwardly facing impact surface.

5. In a downhole tool for delivering a longitudinally directed impact force between a tubular housing and a tubular mandrel reciprocally disposed in the tubular housing, the combination of:

a lower cylindrical knocker ring connected to the upper end of the housing having a internal diameter greater than the external diameter of the portion of the mandrel reciprocating therein to form an upwardly facing, annular groove and having an upwardly facing impact surface at the end thereof,

an upper cylindrical knocker ring connected to the tubular mandrel having an internal diameter greater than the external diameter of the portion of the mandrel reciprocating in the housing to form a downwardly facing, annular groove, and having a downwardly facing impact surface for impacting the upwardly facing impact surface, and

a wiper ring secured within the upwardly facing annular groove having a lip extending upwardly therefrom and engaging the outer periphery of the tubular mandrel at a point substantially above the upwardly facing impact surface.

6. The combination defined in claim 5 wherein:

the upper end of the lower knocker ring and the upper surface of the wiper ring provide a substantially continuous surface which slopes downwardly and outwardly form the tubular rod.

7. The combination defined in claim 6 wherein:

the wiper ring has a lower portion within the lower knocker ring that has a greater diameter than an upper portion above the upwardly facing impact surface, and

the lower knocker ring includes a protector portion which extends over a substantial portion of the upper surface of the wiper ring.

8. The combination defined in claim 7 wherein:

the protector portion is a separate ring which secures the wiper ring in place.

9. In an apparatus for operation in a fluid containing entrained abrasive material, the combination of:

a tubular housing member,

a rod member reciprocally disposed in the tubular housing member,

resilient annular sealing means disposed between the members to provide an annular fluid seal between the members,

one of the members terminating at a point above the sealing means,

a wiper ring secured to the upper end of said one of the members having a lip extending into peripheral engagement with said other member at a point substantially above the end of said one member, and

means for filling the annular space between the members,

the annular sealing means and the wiper ring with a substantially noncompressible lubricating fluid.

10. The combination defined in claim 9 wherein:

the wiper ring and the end of said one member form a substantially continuous surface which slopes downwardly and away from said other member.

11. The combination defined in claim 9 wherein:

the wiper ring is secured to the tubular housing.

12. In an apparatus for operation in a fluid containing entrained abrasive particles, the combination of:

a housing member having a cylindrical bore,

a rod member reciprocally disposed in the cylindrical bore,

resilient annular sealing means disposed between the members to provide an annular fluid seal between the members,

a wiper ring secured to one of the members having a lip extending into peripheral engagement with the other member, and

a substantially noncompressible lubricating fluid filling the annular space formed between said members, the sealing means and the wiper ring.

13. In an apparatus for operation in a fluid containing entrained abrasive material, the combination of:

a tubular housing member,

a tubular rod member reciprocally disposed in the tubular housing member to provide a fluid passageway through the housing member and rod member,

resilient annular sealing means disposed between the members to provide an annular fluid seal between the members,

one of the members terminating at a point above the sealing means, and

a wiper ring secured to the upper end of the rod member having a lip extending into peripheral engagement with said other member at a point substantially above the end of said rod member.

14. In an apparatus for operation of a fluid containing entrained abrasive material, the combination of:

a tubular housing member,

a rod member reciprocally disposed in the tubular housing member,

resilient annular sealing means disposed between the members to provide an annular fluid seal between the members,

one of the members terminating at a point above the sealing means,

a wiper ring secured to the upper end of said one of the members having a lip extending into peripheral engagement with said other member at a point substantially above the end of said one member, and

first port means on one side of the tubular housing for filling the annular space between the members, the annular sealing means and the wiper ring with a substantially noncompressible lubricating fluid and means for closing the first port to retain the fluid during operation.

15. The combination defined in claim 14 further characterized by:

second port means on the opposite side of the housing for flushing said annular space with fluid, and means for closing the second port to retain fluid within said annular space during operation. 

1. In a drilling tool for delivering a longitudinally directed impact, the combination of: a tubular housing, a tubular mandrel reciprocally disposed in the housing and extending above the housing, a resilient fluid sealing ring disposed within the housing and around the mandrel to provide a peripheral fluid seal between the upper end of the housing and the mandrel, an upwardly facing impact surface formed at the upper end of the housing having an internal diameter greater than the external diameter of the mandrel, a downwardly facing impact surface formed around the mandrel above the housing for engaging the upwardly facing impact surface and having an internal diameter at the lower end greater than the external diameter of the portion of the mandrel reciprocally disposed in the housing to form a downwardly facing annular groove, and a wiper ring secured within the housing, the wiper ring having a lip which extends upwardly and engage the periphery of the mandrel at a point above the upwardly facing impact surface and the downwardly facing impact surface when the two surfaces are in contact.
 2. The combination defined in claim 1 further characterized by: port means formed in the mandrel above the downwardly facing impact surface extending between the downwardly facing annular groove and the exterior of the mandrel to vent fluid from the downwardly facing annular groove as the jar closes.
 3. The combination defined in claim 1 wherein: the upper end of the housing tapers downwardly and outwardly from the lip of the wiper ring to the upwardly facing impact surface.
 4. The combination defined in claim 1 further characterized by: a protector ring secured to the housing within the upwardly facing impact surface for protecting a portion of the lip of the wiper ring, the upper surface extending from the wiper ring at a point below the upper end of the lip downwardly and outwardly to the upwardly facing impact surface.
 5. In a downhole tool for delivering a longitudinally directed impact force between a tubular housing and a tubular mandrel reciprocally disposed in the tubular housing, the combination of: a lower cylindrical knocker ring connected to the upper end of the housing having a internal diameter greater than the external diameter of the portion of the mandrel reciprocating therein to form an upwardly facing, annular groove and having an upwardly facing impact surface at the end thereof, an upper cylindrical knocker ring connected to the tubular mandrel having an internal diameter greater than the external diameter of the portion of the mandrel reciprocating in the housing to form a downwardly facing, annular groove, and having a downwardly facing impact surface for impacting the upwardly facing impact surface, and a wiper ring secured within the upwardly facing annular groove having a lip extending upwardly therefrom and engaging the outer periphery of the tubular mandrel at a point substantially above the upwardly facing impact surface.
 6. The combination defined in claim 5 wherein: the upper end of the lower knocker ring and the upper surface of the wiper ring provide a substantially continuous surface which slopes downwardly and outwardly form the tubular rod.
 7. The combination defined in claim 6 wherein: the wiper ring has a lower portion within the lower knocker ring that has a greater diameter than an upper portion above the upwardly facing impact surface, and the lower knocker ring includes a protector portion which extends over a substantial portion of the upper surface of the wiper ring.
 8. The combination defined in claim 7 wherein: the protector portion is a separate ring which secures the wiper ring in place.
 9. In an apparatus for operation in a fluid containing entrained abrasive material, the combination of: a tubular housing member, a rod member reciprocally disposed in the tubular housing member, resilient annular sealing means disposed between the members to provide an annular fluid seal between the members, one of the members terminating at a point above the sealing means, a wiper ring secured to the upper end of said one of the members having a lip extending into peripheral engagement with said other member at a point substantially above the end of said one member, and means for filling the annular space between the members, the annular sealing means and the wiper ring with a substantially noncompressible lubricating fluid.
 10. The combination defined in claim 9 wherein: the wiper ring and the end of said one member form a substantially continuous surface which slopes downwardly and away from said other member.
 11. The combination defined in claim 9 wherein: the wiper ring is secured to the tubular housing.
 12. In an apparatus for operation in a fluid containing entrained abrasive particles, the combination of: a housing member having a cylindrical bore, a rod member reciprocally disposed in the cylindrical bore, resilient annular sealing means disposed between the members to provide an annular fluid seal between the members, a wiper ring secured to one of the members having a lip extending into peripheral engagement with the other member, and a substantially noncompressible lubricating fluid filling the annular space formed between said members, the sealing means and the wiper ring.
 13. In an apparatus for operation in a fluid containing entrained abrasive material, the combination of: a tubular housing member, a tubular rod member reciprocally disposed in the tubular housing member to provide a fluid passageway through the housing member and rod member, resilient annular sealing means disposed between the members to provide an annular fluid seal between the members, one of the members terminating at a point above the sealing means, and a wiper ring secured to the upper end of the rod member having a lip extending into peripheral engagement with said other member at a point substantially above the end of said rod member.
 14. In an apparatus for operation of a fluid containing entrained abrasive material, the combination of: a tubular housing member, a rod member reciprocally disposed in the tubular housing member, resilient annular sealing means disposed between the members to provide an annular fluid seal between the members, one of the members terminating at a point above the sealing means, a wiper ring secured to the upper end of said one of the members having a lip extending into peripheral engagement with said other member at a point substantially above the end of said one member, and first port means on one side of the tubular housing for filling the annular space between the members, the annular sealing means and the wiper ring with a substantially noncompressible lubricating fluid and means for closing the first port to retain the fluid during operation.
 15. The combination defined in claim 14 further characterized by: second port means on the opposite side of the housing for flushing said annular space with fluid, and means for closing the second port to retain fluid within said annular space during operation. 